This invention relates generally to self-contained oxygen breathing apparatus and more particularly to breathing apparatus intended for medical application.
It is believed that up to 11.5 million people in the United States suffer intermittently with some form of migraine headache, the most common type of vascular headache. Historically, drug treatments have been less than 50% effective and have had strong negative side effects. Glaxo's "Sumatriptan", newly approved by the Federal Drug Administration, seems to be a great improvement. It may reduce headache pain in 75% of patients in one or two hours, and has fewer side effects than earlier drugs.
Overlooked or neglected since its discovery as a migraine treatment more than half a century ago is the administration of pure oxygen to the patient. It is well documented that oxygen relieves most cluster headaches within 30 minutes with absolutely no side effects. This form of treatment hasn't been popular with most physicians because of the inconvenience and expense of oxygen delivery from a cylinder.
The satisfaction of the need of migraine sufferers for more convenient and less expensive oxygen delivery systems depends on finding a suitable chemical reaction for generating oxygen that utilizes low-cost chemicals and an associated low-cost apparatus for containing the chemical reaction and delivering the oxygen to a face mask.
One possible source of oxygen are the chlorates and perchlorates of lithium, sodium, and potassium, which give off oxygen when heated. Chlorate candles, a combination of the oxygen-producing material, a fuel, a material that absorbs trace amounts of chlorine, and an inert binder, have been used as oxygen sources in submarines and airplanes and have many desirable characteristics. Unfortunately, they are not inexpensive.
The peroxides of sodium and potassium in combination with carbon dioxide and water vapor decompose into oxygen and water vapor. A catalyst such as nickel sulfate is required to obtain total decomposition of the peroxides. A conceptually-simple oxygen breathing system is obtained by circulating the exhaled breath of a user through the peroxide and back to the user for inhalation.
The peroxides have the advantage of not only producing oxygen but also absorbing the carbon dioxide in the user's exhaled breath. The peroxides are not very oxygen-weight efficient and breathing apparatus based on peroxides are usually supplemented with bottled oxygen.
The alkali metal superoxides react with water vapor to form oxygen and the metal hydroxide. The metal hydroxide reacts with carbon dioxide to form the carbonate, the bicarbonate, and water vapor.
The superoxides also have the advantage of generating oxygen and absorbing carbon dioxide. Breathing apparatus based on the superoxides do not require any auxiliary source of oxygen.
Sodium percarbonate when combined with water and a catalyst such as manganese dioxide decomposes into sodium carbonate, oxygen, and water. Since this reaction is strongly exothermic, the oxygen is released at high temperature and part of the water is turned into steam.
The oxygen produced in this way cannot be directly used for human respiration because of its high temperature and excessive humidity. Consequently, any breathing apparatus based on this chemical reaction must incorporate a heat exchanger to cool the oxygen.
Breathing apparatus based on the above-described chemical reactions are beyond the reach of most migraine sufferers either because of the cost of chemicals or the cost of the apparatus necessary to support the chemical reaction.